Filter



July 14 194% H. w. DENHARD Erm. '2,289,411

Y FILTER n Filed umn e, 1959 l l Z5 23 M HAI/eey mg @iN/mea ATTORNEY.

Patented July 14, 1942 s FILTER Harry W. Denhard, Berkeley, and OrvilleA B. Ackerly, Jr., Piedmont, Calif., assignors to Oliver United Filters Incorporated, San Francisco, Calif., a corporation of Nevada.

Application March 6, 1939, SerialNo. 260,106

9 Claims.V (Cl. 21u- 499) This invention relates in general to filters and more particularly to the construction of a filter cell or compartment of arota'ry drum filter.

The surface of a rotary drum filter is divided into a series of contiguous independent filtrate cells or compartments by a plurality of spaced longitudinally extending parallel division strips secured to the drum. When using an all metalconstruction, considerable dii'culty has been experienced in welding the division strips to the drum, for it has been foundthat the welding operation results in warpage of the division strip as well as of the drum. This is of course objectionable, for to operate kin conjunction with a discharge scraper, scroll,` or roll, the surface of the drum must be true.

The filter medium of a rotary drum filter is held in spaced relation with respect to the drum by a drainage or supporting screen. Oftentimes itis desirable to replace this screen or remove it in order to'clean the drum.

In general the object of this invention is the y gage of the metal fromwhich the drum is made.

portionate to its gage.

provision of a drum construction wherein the division strips may be welded to the drum without causing any distortion in the drum or division strips and wherein the supporting screen may beflrmly but detachably secured between adjacent division strips. AThe invention possesses other advantageous features,.s'ome of which with the foregoing will be set forth at length in the following description Where those forms of the invention Whichv have been selected for illustration in the drawing accompanying and forming a part of the present specification are outlined in full. Inzsaid drawying, three forms of the invention are shown, but it is to be understood that it is not limited to such forms, since the invention as set forth in the claims may be embodied ina plurality of forms. Referring to the drawing: Figure 1 is a fragmentary vertical section of the drum of a rotary drum filter showing one of the filtrate compartments formed by adjacent division strips and also showing a tool for springing the supporting screen into place.

Figure 2 is a section taken on the line' 2-2 of Figure 1.

Figure 3 is a plan view of the structure shown in Figure 1. l

Figure 4 is a partial vertical section `taken through the drum of a rotary drum filter and showing amodifled form of division strip and supporting screen. f

Figure 5 is a partial vertical section taken through the drum of a rotary drum filter and showing still another modification of the supporting screen. l

As shown inI ,Figure 1, the objects of my invention are embodied in a filter comprising a ductile metal drum I, to the outer surfaceof which are welded a plurality of spaced division strips 2 servingwith the drum I to define adjacent filtrate compartments 3. The division strip 2 may conveniently be made by rollingv a sheet of ductile metal into a bar formed with a concave bottom face 4, a central channel 5,-- and two opposed lateral channels 6 and 1. The division strip 2 is welded to the drum I along the edges 8 and 9of the division strip and the gage of the metal from which the division strip is made should not be greater than-onethird the This ratio is of importance for the following reasons:

The heat dissipated by a sheet of metal is pro- The greater the gage of the metaLthe greater the dissipation of heat and consequently the greater thenumber of calories required to bring the metal to a given temperature withina given time. The heat required to bring a sheet of metal up to the Welding temperature likewise varies with the gage of the.

It therefore follows that by making the division strip relatively thin at the point at which metal.

it is to be welded to the drum, a'weld can be made without increasing the temperature of the drum at this point to such an extent that it is distorted by its resulting expansion or to such an extent that it is insufficiently rigid to prevent the division strip from becoming distorted. A1-

though a division strip of rolledmetal has been shown, obviously this result is not dependent.

upon the manner in which the division strip is fabricated, that is, whether it is made by rolling or drawing a sheet of metal or by milling a bar of metal, so long as that portion of vthe division l strip in contact with the drum is relatively thin as compared to the drum.

Defining the upper limits of the lcompartment 3 is a supporting screen Ilmade of a'perforated plate and provided along each edge with offsets I2 and I3 adapted to be accommodated within the lateral channels 6 and 1 of the division strips 2. After the 'offset edge I2 of the supporting screen Il Vhas been inserted within the laterally extending channel of its `associated ydivision strip, its

offset I3 may be sprung into the channel 1 of the opposed divisionstrip by the pair of tongs generally designated, as I4. These tongs consist of a -base member .I5 having a downwardly projecting portion I6 adapted to be accommodated within the channel 5 of a division strip, and an operating member I1 pivoted thereto and provided at one end with a number of pins I8 adapted to be inserted in the apertures of the supporting screen II. Welded' tothe lower face' of the supporting screen I I in spaced parallel relation are a number of corrugated spacing members I9 o f such depth that the outer surface of the screen. II is level with the outer surfaces of the division strips 2. The location of the lateral channels 6 and 1 formed in the division strips 2 and the depth of the offsets I2 and I3 along the lateral edges of the supporting screen II are so related that the outer surface of the supporting screen IIv is flush with the outer surfaces of the division st rlps 2.

The filter medium, which has not been shown in Figures 2 and 3, may then be disposed over the surfaces of the supporting screens I I and secured within the channel of the division strip in any suitable and well known manner.

-InFigure 4 a modified form ofour invention is embodied in a filter comprising a drum 2I having welded to its outer surface a plurality of parallel spaced division strips 22. The division strip 22 is formed of rolled metal and is provided with and screen in spaced relation.

3. A lter comprising; a compartment defined in part by a floor, and a pair of spaced side members secured thereto and each provided with a laterally extending channels 23 and 24 imf mediately above its base members 25 and 26 and with an undercut channel 2l formed in its upper surface. A perforated supporting screen 28 provided with corrugated spacing members 29 is adapted to be secured alng each of its lateral edges to the division strips 22 by L-shaped clips 3| arranged to be accommodated within the laterally extending channels 23 and 24 of the division strip. This construction is generally similar to the construction shown in Figures 1, 2, and 3, with the exception that the L-shaped-clips have been substituted for the offsets I2 and I3 shown in Figures 1, 2, and 3, and that the lateral channels 24 and 25 of Figure 4 are adjacent the base of the division strip 22, whereas the laterally extending channels 6 and 'Iv of the division strip 2 are located adjacent the upper surfacev of the division strip. Ifas'shown in Figure 4, the supporting screen 28 is covered with a ne mesh Wire screen 32, the location of the laterally extending channels 24 and 25 and the clip 3I is such that the outer'surface o f the screen 32 is level with the outer surface of the division strip 22.

The construction shown in Figure 5 is identical with that shown in Figure 4 with the exception that a Z-shaped clip 4I has been substituted for the L-shaped clip shown in Figure' 4.

From the above description it will be seen thatwe have provided a drum construction wherein the division strips may be welded to the drum without the usual danger of distorting one or both of these elements, wherein the supporting screen may be rigidly but readily attached to the drum and its associated division strips, and

wherein the supporting screen may be readily detached from its associated members.

We claim:

1. A filter comprising: a filtrate compartment defined in part by a base member and a pair of spaced side members secured to said base member and each provided with laterally extending overhanging portions; a resilient supporting screen having a length greater than the distance between said overhanging portions, disposed within said compartment and secured to said side members by having its ends sprung beneath said overhanging' portions; and spacing means' for holding said base members and screen in spaced relation.

2. A filter comprising: a compartment defined in part by a base member and a pair of spaced side members secured to said base member and lateral longitudinally extending channel; a resilient supporting screen having a length greater than the distance between said side members, disposed witl'iin said compartment and secured to said side members by having its ends sprung into the lateral channels of the side members; and means associated with said screen for holding said screen and floor in spaced relation.

4. A filter comprising: a compartment defined in part by a backing plate and spaced division strips secured to said backing plate, each of said division strips having a lateral channel extending longitudinally thereof; and a resilient supporting screen disposed within said compartment and provided with spacing members secured to its lower surface, the ends of said supporting screen being provided with offset extensions arranged to be swung into the lateral channels of said division strips. v

5. A filter comprising: a drum; a plurality of division strips secured to the outer surface of said drum in spaced relation and parallel to its axis; rabbets formed in the sides of said division strips; resilient supporting screens of greater length than the distance between said division strips sprung between adjacent division, strips with their longitudinal edges disposed within said rabbets; and spacing means for holding said screens in spaced relation with said drum. y

6. A filter comprisingfz/ a filtrate compartment dened in part by a pair of spaced side members, each provided with laterally extending overhanging portions; a resilient supporting screen disposed within said compartment and provided along its lateral edges with downwardly and outwardly extending offsets adapted to be sprung beneath said overhanging portions to detachably secure said screen to said side members.

7. A filter comprising: a compartment defined in part by a ductile metal backing member, a pair of spaced ductile metal side members each welded to said backing member by a base having a gage not greater than one-third the gage of said backing member, and end members secured to said backing member; a lter medium disposed over said compartment; and means for holding said filter medium spaced from said backing member.

8. A rotary drum filter comprising: a drum made of ductile metal; and a plurality of spaced parallel ductile metal division strips each welded to said drum by a base member having a gage not greater than one-third the gage of said drum. t

9. A rotary drum filter comprising: a drum made of ductile metal and a ductile metal division strip welded thereto by a base having a gage not greater than one-third the. gage of said drum.

HARRY W. DENHARD. ORVILLE B. ACKERLY, JR. 

